1964 Chevy Malibu SS - Rust- B-Gone

Installing A New Goodmark Chevelle Trunk Floor

Pop the trunk of your just-purchased musclecar and oh no! The trunk's floor is rusted, there's a musty smell, and the water collecting on the bottom of the trunk lid is dripping down. What happened? Well, before you start worrying that your latest and coolest ride is turning back to earth, take heed, because many Chevelles have suffered this fate.

As designed, the rear window of a typical '64-72 Chevelle features a hidden trough just below the rear window's lower stainless molding, which does not drain. When water runs onto the car, it naturally collects under this molding and remains there until it evaporates. This can take days-even weeks-to dry out, and each time the car gets wet the water travels into the trough again. Over time, this sitting water rusts the metal until the water has a passageway to leak into the trunk. On convertible models, the water's path to the trunk may open up even sooner, because the water typically has a less complicated path to negotiate.

Once water arrives unnoticed in the trunk, the large vinyl factory mat traps the water between it and the top of the trunk's floor. After several years of moisture accumulation, the trunk floor is next in line to rust away, just as the lower rear-window sash did a few years earlier. Whether your car is from the Snow Belt or the deserts of the Southwest, chances are water has attacked the trunk floor of your Chevelle, leaving rusted-through metal. In many cases, you even see the top of the fuel tank and/or the bracing below the trunk panel.

As relentless and extensive as this damage is, it's good to know that the repair is straightforward. With a day or two of work, new trunk floor panels, and some common body-shop equipment, you can make your trunk's floor new again. Of course, while you're tackling this project you should also take a look at your back widow sash's condition and repair that as needed.

But for this story we're sticking to the ins and outs of trunk floor replacement. Our candidate for this is a '64 Malibu SS convertible that, although a Southern California car since new, has suffered the same rust problems that many other Chevelles have everywhere. With our new trunk floors from Goodmark Industries and a few tools, we'll have this Chevelle's trunk looking better than new.

It's In The TrunkHere's a quick rundown of what we used for this story. If your left- and right-side trunk drop-offs are rusted, Goodmark offers those as well. The '64-67 seven-piece trunk floor kit includes three floor sections, two body-mount braces, and two gas-tank braces, and it covers an area approximately 67.5 inches wide by 40.5 inches long.

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1964 Chevy Malibu SS - Rust- B-Gone

The floor of this '64 A-body had water trapped below the trunk's vinyl mat for years. The bottom of the trunk was rusted so badly that the top of the fuel tank was exposed. This is not only ugly but also unsafe, because engine exhaust can travel through these openings and into the passenger compartment.

Before doing any repairs to the trunk floor, we first removed the fuel tank. To do this, disconnect the battery, remove the wires from the sending unit, and drain, loosen, then remove the tank. A big piece of plywood located next to the car is a good place to set the tank immediately after removing it.

Inside the trunk, we mapped out the area to be replaced with a felt pen. With a rotary cutting wheel, the area was carefully cut. The entire area of this trunk did not need to be replaced, so the area that was being removed was somewhat smaller than the new panels, which were trimmed to fit. Don't be tempted to use an air chisel to trim the floor-the cut edge will be far less accurate. Air chisels (if used properly) will work well in some applications, such as separating parts of the trunk floor from frame sections on unibody Camaros and Novas.

This rusted old floor has been completely removed. On Chevelles or Impalas, be careful not to cut into the rear framerails when removing the trunk floor, and on Camaros or Novas, watch out for the rear longitudinals (unibody frame areas). With the rusted panels removed, we cleaned off the edges from the existing floor with a grinding disc so that we could get a good weld between it and the new panels.

The Goodmark kit includes the floor, body-mount braces, and gas-tank braces, which are all Electro Deposit Primer (EDP) coated for long life. The EDP process works on the principle that materials with opposite electrical charges attract each other. During the application process, the airborne paint particles are drawn with electric current to the metal and the paint is charged to the part, forming an even film over every surface. The EDP coating has been tested for 500 hours under a salt-spray solution to check for corrosion. This is far superior to spray-on primers.

We carefully positioned the old panel over the new one prior to installation and outlined the edges. Next, metal shears were used to cut the new panels to match the section removed from the Chevelle's trunk floor.

The old, rusted braces were removed and new ones positioned and welded in place. We used big Vise-Grips to hold the braces securely during welding.

We used a wire-feed MIG-welder to weld the lower braces into the original positions.

Before the panels were welded in place, they were first test-fitted, hammered, and dollied to correct any misalignment. We cut our panels to be about 11/48 inch larger than the opening in the trunk area and then ground the edges with a rotary sander to provide a clean welding area.

In this case, the panel was trimmed with a rotary grinder to fit the floor.

After the panel was in place it needed to set flush before welding. With the lower braces already installed, we climbed on top of the new floor (to hold it down) and started our initial spot welds. A MIG-welder is used because it produces the most localized heat zone, minimizing distortion.

For this installation, we skip-welded the panels in place, then grounded the welds smooth. From there we scuffed and cleaned the entire area, top and bottom. Next we applied an EDP-friendly primer to the new panels and welded surfaces.

We applied seam sealer to the top and bottom areas that were welded together. This further protects the welds and gives the repair a factory-type appearance. Seam sealers are available from automotive body-shop supply stores and are typically applied with a heavy brush.

For our final step, we applied a few coats of primer, making the entire area look new again. Best of all, the new Goodmark Industries trunk floor, with its EDP coating, is actually more rust-resistant than the original and will last for years to come. CHP

Check out Brent Jarvis of Performance Restorations 1965 Chevy Malibu SS. Under the hood Brent stuffed a LS6 476 big block with Hedman headers. Only at www.chevyhiperformance.com, the official site for Chevy High Performance Magazine. » Read More